From mboxrd@z Thu Jan 1 00:00:00 1970 From: Philipp Zabel Subject: [PATCH v7 0/4] Add generic driver for on-chip SRAM Date: Fri, 23 Nov 2012 15:24:11 +0100 Message-ID: <1353680655-21624-1-git-send-email-p.zabel@pengutronix.de> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Arnd Bergmann , Greg Kroah-Hartman , Grant Likely , Rob Herring , Paul Gortmaker , Shawn Guo , Richard Zhao , Huang Shijie , Dong Aisheng , Matt Porter , Fabio Estevam , Javier Martin , kernel@pengutronix.de, devicetree-discuss@lists.ozlabs.org List-Id: devicetree@vger.kernel.org These patches add support to configure on-chip SRAM via device-tree node or platform data and to obtain the resulting genalloc pool from the physical address or a phandle pointing at the device tree node. This allows drivers to allocate SRAM with the genalloc API without hard-coding the genalloc pool pointer. The on-chip SRAM on i.MX53 and i.MX6q can be registered via device tree and changed to use the simple generic SRAM driver: ocram: ocram@00900000 { compatible = "fsl,imx-ocram", "sram"; reg = <0x00900000 0x3f000>; }; A driver that needs to allocate SRAM buffers, like the video processing unit on i.MX53, can retrieve the genalloc pool from a phandle in the device tree using of_get_named_gen_pool(node, "iram", 0) from patch 1: vpu@63ff4000 { /* ... */ iram = <&ocram>; }; The allocation granularity is hard-coded to 32 bytes for now, until a way to configure it can be agreed upon. There is overhead for bigger SRAMs, where only a much coarser allocation granularity is needed: At 32 bytes minimum allocation size, a 256 KiB SRAM needs a 1 KiB bitmap to track allocations. Once everybody is ok with it, could the first two patches be merged through the char-misc tree? I'll resend the i.MX and coda patches to the respective lists afterwards. Changes since v6: - Reduced the hard coded allocation granularity to 32 bytes. regards Philipp --- Documentation/devicetree/bindings/misc/sram.txt | 17 ++++ arch/arm/boot/dts/imx53.dtsi | 5 + arch/arm/boot/dts/imx6q.dtsi | 6 ++ drivers/media/platform/Kconfig | 3 +- drivers/media/platform/coda.c | 47 ++++++--- drivers/misc/Kconfig | 9 ++ drivers/misc/Makefile | 1 + drivers/misc/sram.c | 121 +++++++++++++++++++++++ include/linux/genalloc.h | 14 +++ lib/genalloc.c | 67 +++++++++++++ 10 files changed, 274 insertions(+), 16 deletions(-)